1) The point contact steel wire rope adopts equal diameter steel wire. Due to the uneven laying distance of each layer of steel wire, point contacts are formed between each layer of steel wire. Steel wire has high contact stress under load, is prone to wear and fracture, and has a low service life. Its advantages are simple manufacturing process and low price. Commonly used as binding rigging for lifting operations, it can also be used as a working mechanism for cranes.
2) The contact steel wire rope is made of steel wires of different diameters, and the inner and outer steel wires are prepared properly to form contact between different steel wire layers. Thus reducing the contact stress of the steel wire under load. Steel wire rope has high load-bearing capacity, good flexibility, and long service life when in contact with steel wire rope. Commonly used in Warrington style, Westland style, filling style, etc., recommended in crane design specifications and widely used in crane working mechanisms.
3) The surface contact steel wire rope is generally made of round steel wire as the core, and the outer layer or layers are extruded with steel wire of special cross-section. It has the characteristics of smooth surface, good flexibility, high strength, and corrosion resistance, but its manufacturing process is complex and expensive, and it is rarely used on cranes. Use cable cranes and overhead cableways to support the load-bearing cables.
4) The selection of steel wire rope should meet the requirements of sufficient bearing capacity and service life.
The calculation of steel wire rope adopts numerical method to calculate the static tension under working conditions. The formula is as follows:
In the formula, f0 is the total breaking force calculated for the steel wire rope (refer to the steel wire rope performance table);
Twisting loss coefficient of steel wire rope (refer to the performance table of steel wire rope);
Determine based on the work level or purpose of the work organization.
Note: Steel wire ropes used for lifting dangerous goods generally use a working level coefficient higher than the design working level.
Service life of steel wire rope. In order to improve the service life of steel wire ropes, attention should be paid to the design of the winding system. The ratio of the diameter of the supporting pulley and drum to the diameter of the steel wire rope has a significant impact on the service life of the steel wire rope, and should not be lower than the value specified in the design specifications; The pulley and drum should be made of cast iron material to prevent damage to the steel wire rope due to the material being too hard; The bending frequency of steel wire rope should be minimized as much as possible to avoid reverse bending. Strengthen the maintenance and upkeep of steel wire ropes during use.
